This invention relates generally to printed circuits and in particular to a flexible ribbon cable for interconnecting portions of a display system such as between a matrix display element and it drive electronics.
Prior packaging techniques for electronic equipment have typically involved mounting active and passive electronic components on a single layer or multilayer printed wiring board (PWB). A plurality of such printed wiring boards are interconnected by plugging the plurality of boards into a "mother" interconnect panel. In some applications where space is at a premium the interconnect panel is replaced by straight runs of flexible ribbon cable such as in a flat panel matrix display system for interconnecting the contacts on the edge of a display element to the contacts on the edge of a display drive electronics printed wiring board. Typically there may be between 500 to 6000 electrical connections between the display element and the drive electronics resulting in considerable space required for the drive electronics, significant assembly costs and limits on the degree of maintainability in the field. If connections between the drive electronics and the display element need to be undone in the field for testing or replacement of only a single inexpensive faulty device, the display assembly must be returned to a service center for reassembly. As a result, the display element and drive electronics are spared in the field as a single line replaceable unit (LRU), which is expensive. If the display system parts are designed to be readily separable, then repair of the drive electronics is feasible in the field requiring only the sparing of relatively inexpensive parts or devices.
The high voltage driver circuits have accounted for most of the drive electronics volume requirements in a matrix display system. The packaging of high voltage driver circuits in a leadless chip carrier (LCC) configuration can achieve significant volume reductions in such a display system; however, an assembly problem arises if a surface mounted LCC and conventional thru-board integrated circuit (IC) devices such as dual in-line packages (DIPS) are mounted on the same printed wiring board because two incompatible assembly techniques are required. This approach by itself does not reduce the large number of interconnections required between the display drive electronics and the display element.